In general, semiconductor devices may be manufactured by performing, on the basis of a wafer including a thin single crystalline substrate of a silicone material, a FAB process for forming a plurality of chips with circuit patterns patterned on the wafer, a bonding process for electrically connecting each of the chips formed through the FAB process, a molding process for protecting the chips connected to the substrate from the outside, and the like. Here, the wafer is prepared in such a way that a cylinder-shaped ingot is thinly sliced, and a polishing process for smoothing a surface of the wafer is then performed.
Recently, as semiconductor devices are highly integrated, it is difficult to decrease the surface roughness of a wafer only through a polishing process on the surface of the wafer. Accordingly, it is difficult to realize a circuit pattern having a fine line width, specifically approximately 12 nm to approximately 16 nm, on the wafer. Therefore, an epitaxial process is further performed with respect to the wafer on which the polishing process is performed, such that the surface roughness of the wafer is decreased to a level of approximately 30% or further to approximately 50%.
Here, the epitaxial process is performed by using an epitaxial apparatus including: a process chamber into which a silane gas is injected; a susceptor on which a wafer on which a polishing process has been completed inside the process chamber is placed; a lift pin driven to move up and down while passing through holes of the susceptor to place the wafer on the susceptor or space the wafer apart from the susceptor; and a heater providing the inside of the process chamber with heat such that the wafer is heated to a temperature of approximately 1000° C. to approximately 1400° C.
Specifically, the epitaxial process is performed in such a manner that the silane gas provided into the process chamber reacts with the wafer surface through the heat from the heater to grow a crystal, and then the growing crystal fills clearances on the wafer surface. Therefore, a thin film of approximately several microns is formed on the wafer surface, thereby decreasing the surface roughness of the wafer or removing defects on the wafer to obtain a high-quality wafer. Here, while the epitaxial process is performed, the wafer is heated by means of the heater to a high temperature of approximately 1000° C. to approximately 1400° C., and thus a small bending phenomenon cannot but occur in the wafer.
Since the bending phenomenon occurs while the lift pin directly contacts and supports the wafer, the lift pin may also generates a scratch on the wafer in which the bending phenomenon occurs. Further, since the lift pin is driven to move up and down along the hole of the susceptor, vibration is generated by the friction between the lift pin and the susceptor, and a scratch, a dent, a ground out, or the like may occur. Since the wafer is damaged by a scratch, a dent, a ground out, or the like and particles are generated due to the damage to the wafer, the surface quality of the wafer may be deteriorated. Also, the quality of the thin film formed on the wafer surface by the epitaxial process may be deteriorated.